<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>demo2-14</title>
    <script src="vue.js"></script>
</head>
<body>
    <div id="app">
        <h3>银行帐户余额变更通知</h3>
        <p>帐号：3001237890122</p>
        <p>余额为：{{count}}</p>
        支取人民币：<input type="text" v-model="money"/> &nbsp;&nbsp;
        <button type="button" @click="changeMoney()">支取{{money}}元</button>
        <p>支取后余额为：{{count}}元</p>
        <h3>支取明细</h3>
        {{detail}}
        <hr>
    </div>
</body>
<script type="text/javascript">
    const appCom = {
        data(){
            return {
                count: 10000,
                money: 400,  
                record: []  
            }
        },
     
        watch: {
        
            count(newValue, oldValue) {
                alert('帐户余额由 :' + oldValue + ' 变为 ' + newValue + '元!');
            }
        },
        
        methods: {
           
            changeMoney() {
                if(this.money <= 0){
                    alert('请输入正确取款金额!');
                    return;
                }
                if(this.money > this.count){
                    alert('余额不足，请重新输入取款金额!');
                    return;
                }
               
                this.count = this.count - this.money;
               
                this.record.push(this.money);
            }
        },
      
        computed:{
            
            detail(){
                let str = '';
                for(let i = 0; i < this.record.length; i++){
                    str = str + '第' + (i + 1) + '次取款：' + this.record[i] + '元; ';
                }
                return str;
            }
        }
    };
    
    Vue.createApp(appCom).mount("#app");
</script>
</html>
